If I remember correctly, it is the 3rd answer choice.
Answer:
1. Luminosity
2.Apparent brightness
Explanation:
There are two factors on which brightness of star appear to be in the sky
The two factors are
1. Luminosity
2.Apparent brightness
1.Luminosity :It is defined as the total energy emitted by the object in a given time.Luminosity vary with the distance of observer from the star.Luminosity is a intrinsic property which depends on the fundamental chemical composition and structure of the material.Luminosity is depends on the size of star.Lager the star luminosity will be more.
2.Apparent brightness: It is defined as how bright a star appears from an observer on the earth and the amount of starlight reaching the earth.if the distance is large then the brightness decreases.When the distance of star from us small then the brightness of star increases.Distance is inversely proportional to brightness of the star.
The centripetal acceleration is 
Explanation:
For an object in uniform circular motion, the centripetal acceleration is given by

where
v is the speed of the object
r is the radius of the circle
The speed of the object is equal to the ratio between the length of the circumference (
) and the period of revolution (T), so it can be rewritten as

Therefore we can rewrite the acceleration as

For the particle in this problem,
r = 2.06 cm = 0.0206 m
While it makes 4 revolutions each second, so the period is

Substituting into the equation, we find the acceleration:

Learn more about centripetal acceleration:
brainly.com/question/2562955
#LearnwithBrainly
Answer:
1428.6m/s²
Explanation:
Given parameters:
Force applied on the body = 40N
Mass of the body = 28g
1000g = 1kg
28g will therefore be 0.028kg
Unknown:
Acceleration = ?
Solution:
To solve this problem, we use the expression derived from Newton's second law of motion.
Force = mass x acceleration
Insert the parameters and solve;
40 = 0.028 x acceleration
Acceleration =
= 1428.6m/s²